JPH08336248A - Rotor with permanent magnet - Google Patents

Abstract

PURPOSE: To obtain a rotor buried with permanent magnets of two layer structure in which the magnet torque can be utilized effectively by backing up the permanent magnets on the outer circumferential side sufficiently. CONSTITUTION: The rotor 3 comprises a rotor body 3a made of a material having high permeability buried with a plurality of sets of permanent magnets 8a, 8b at an interval of two layers per pole in the radial direction of the rotor. Each of the permanent magnets 8a, 8b has arcuate shape projecting in the centripetal direction of the rotor. Thickness of the permanent magnet 8b located on the inner circumferential side of rotor is set thicker by 3% or more than that of the permanent magnet 8a located on the outer circumferential side of rotor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor with a permanent magnet, in which a plurality of sets of permanent magnets arranged in two layers inside and outside are embedded in a rotor body.

[0002]

2. Description of the Related Art Conventionally, a rotor having a permanent magnet embedded in a rotor body made of a high magnetic permeability material such as iron has been known.

FIG. 3 shows a rotor with a two-layer structure, which is developed by the present inventors to effectively utilize reluctance torque (Japanese Patent Application No. 7-134023). The rotor 3 according to this prior invention includes an iron rotor body 3a,
4 sets of permanent magnets 8a, 8b, etc., which are arranged in two layers per pole in the rotor radial direction with a space, are embedded, and the permanent magnets 8a, 8b of each set have S poles and N poles alternately. Permanent magnets 8 arranged adjacent to each other and in a two-layer relationship
The a and 8b are configured so that the polarities on the outer peripheral side are the same. Each of the outer permanent magnets 8a, ... And the inner permanent magnets 8b, ... Is formed in an arc shape that is convex in the centripetal direction of the rotor, and has an outer permanent magnet 8a and an inner side that are in a two-layer relationship. The permanent magnets 8b are arranged in parallel with each other, and the distance between them is constant.

The permanent magnets 8a and 8b are made of the same magnetic material and have the same radial thickness.

As described above, the rotor 3 in which the permanent magnets 8a located on the outer peripheral side of the rotor and the permanent magnets 8b located on the inner peripheral side of the rotor are embedded in two layers with a space therebetween, is the winding 10 group on the stator 2 side. Generated by the magnetic torque generated by the relationship between the rotating magnetic field generated by the magnetic field of the permanent magnet 8 and the magnetic field of the permanent magnet 8 and the magnetic path formed by the rotating magnetic field being formed on the surface side of the rotor body 3a or in the space between the inner and outer permanent magnets 8b, 8a. It rotates in the R direction by the combined torque with the reluctance torque.

Among the permanent magnets 8 having a two-layer relationship, the magnetic flux that contributes to the magnet torque of the permanent magnet 8a on the outer peripheral side is backed up by the magnetic flux of the permanent magnet 8b on the inner peripheral side. FIG. 4 shows the result of magnetic field analysis by the permanent magnet 8, in which a magnetic path is formed in a loop.

[0007]

In the structure of the above-mentioned prior invention, in consideration of effective use of reluctance torque,
Since there is a gap for the magnetic flux to pass between the permanent magnets 8a and 8b having a two-layer relationship, as shown in FIG.
There is a phenomenon in which magnetic flux emitted from both ends of the inner peripheral side permanent magnet 8b does not enter the outer peripheral side permanent magnet 8a but flows directly to the stator 2 side and does not back up the outer peripheral side permanent magnet 8a. .

Therefore, the backup of the permanent magnet 8b on the inner peripheral side to the permanent magnet 8a on the outer peripheral side is reduced as a whole, and the amount of magnetic flux contributing to the magnet torque generated in the permanent magnet 8a on the outer peripheral side is reduced. Therefore, there is a problem that the magnet torque is reduced.

[0009]

In order to solve the above-mentioned problems of the prior invention, the first invention of the present application arranges two layers per pole in the rotor body made of a high magnetic permeability material in the radial direction of the rotor. A plurality of sets of permanent magnets embedded in the rotor, each of the permanent magnets has an arc shape that is convex in the centripetal direction of the rotor, and is located on the rotor inner peripheral side of the permanent magnet having a two-layer structure. It is characterized in that the thickness of the permanent magnet is 3% or more of that of the permanent magnet located on the outer peripheral side of the rotor.

In order to solve the above-mentioned problems of the prior invention, the second invention of the present application has a plurality of sets of permanent magnets, which are arranged in the rotor main body made of a high magnetic permeability material, in two layers per pole in the rotor radial direction. In a rotor in which magnets are embedded, each of the permanent magnets has an arcuate shape that is convex in the centripetal direction of the rotor, and the permanent magnets located on the rotor inner circumference side of the permanent magnet having a two-layer structure are Side permanent magnets,
It is characterized by being made of a magnetic material having a residual magnetic flux density of 3% or more.

[0011]

The first aspect of the present invention having the above-described configuration can perform the following actions. That is, each of the permanent magnets has an arcuate shape that is convex in the centripetal direction of the rotor, and the thickness of the permanent magnet located on the rotor inner peripheral side of the permanent magnet having a two-layer structure is equal to that of the permanent magnet located on the rotor outer peripheral side. Since the magnet is formed with a thickness of 3% or more, the difference in the thickness raises the operating point that determines the magnetic flux density of the permanent magnet on the backup side. The magnetic flux density emitted from the magnet can be increased. Therefore, as a result of being able to sufficiently back up the permanent magnets on the outer peripheral side of the inner peripheral side even at both ends, it is possible to solve the problem that the magnet torque is reduced, which is a problem of the prior invention. .

The second aspect of the invention of the present application can perform the following actions with the above configuration. That is, the permanent magnet having the above-mentioned two-layer structure is made of magnetic materials having different residual magnetic flux densities of 3% or more, and the permanent magnet made of magnetic material having a large residual magnetic flux density is arranged on the backup side (inner circumferential side). Therefore, as compared with the prior invention, the magnetic flux density emitted from the permanent magnet on the backup side can be increased.
The same operation as that of the invention can be performed.

In the first invention and the second invention of the present application, the thickness of the permanent magnet on the inner peripheral side is 3 with respect to that of the permanent magnet on the outer peripheral side.
If the residual magnetic flux density of the inner peripheral side permanent magnet is less than 3% relative to the outer peripheral side permanent magnet, the backup effect becomes insufficient.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a sectional view showing a first embodiment of the present invention.

The rotor 3 is arranged on the iron rotor main body 3a with two layers per pole in the radial direction of the rotor with a space therebetween.
.. are embedded, and the permanent magnets 8a, 8b of each set are adjacently arranged so that the S poles and the N poles are alternated, and have a two-layer relationship. 8a, 8
b has the same polarity on the outer peripheral side. The outer permanent magnets 8a, ... And the inner permanent magnet 8
Each of b, ... Is formed in an arc shape that is convex in the centripetal direction of the rotor 3, and the outer permanent magnet 8a and the inner permanent magnet 8b that are in a two-layer relationship are arranged in parallel. The distance between them is constant.

The inner peripheral permanent magnet 8b has a thickness Wb shown in the drawing in the radial direction of the rotor 3, and is formed 5% thicker than the outer peripheral permanent magnet 8a.

On the other hand, a plurality of teeth 4 are provided on the stator 2 side, and a winding 10 is arranged between these teeth 4. When an alternating current is applied to the winding 10, a rotating magnetic field is generated. ing.

FIG. 2 is a characteristic graph of H (magnetic field) -B (magnetic flux density), where the vertical axis is the magnetic flux density B and the horizontal axis is the magnetic field H. Here, all the permanent magnets 8a and 8b are shown in FIG.
The material is a neodymium iron magnet having a demagnetization curve shown by. On the line connecting the residual magnetic flux density Br and the coercive force Hc in the figure, the operating point indicated by K1 in the figure of the permanent magnet 8a on the outer peripheral side exists. Further, since the permanent magnet 8b on the inner peripheral side is formed to be thicker than the permanent magnet 8a on the outer peripheral side,
The operating point will rise to the position indicated by K2.

Here, the difference P between K1 and K2 in the figure is the magnetic flux density B
It shows as the difference of. In the first embodiment, K2 is K
It has increased by about 4% compared to 1.

As described above, the permanent magnet 8b on the inner peripheral side has a magnetic flux density of about 4% higher than that of the permanent magnet 8a on the outer peripheral side. Magnetic flux is supplied to the permanent magnet 8a of the
Can be fully backed up.

Next, a second embodiment of the present invention will be described.

In the second embodiment, the inner and outer permanent magnets 8b, 8a are formed to have the same thickness shape, and when viewed only from the shape, FIG.
The same as the prior invention shown in FIG. 2, but with the outer peripheral permanent magnet 8a.
Is formed of a ferrite magnet, and the permanent magnet 8b on the inner peripheral side is formed of a neodymium iron magnet.

In FIG. 2, 11 and 12 respectively show H (magnetic flux) -B (magnetic flux density) characteristics of the neodymium iron magnet (permanent magnet 8b) and the ferrite magnet (permanent magnet 8a). As shown in FIG. 2, the residual magnetic flux density Br of the neodymium iron magnet 11 is equal to the residual magnetic flux density B of the ferrite magnet 12.
It is about 3 times that of r '. The outer permanent magnet 8a has a magnetic flux density determined by the operating point K3 in FIG. 2, and the inner permanent magnet 8b has a magnetic flux density determined by the operating point K1 in FIG.

The difference Q between K1 and K3 is the inner / outer permanent magnet 8
It appears as a difference in magnetic flux densities of b and 8a, and the permanent magnet 8b on the inner peripheral side is about twice or more as large as the permanent magnet 8a on the outer peripheral side. As described above, even if the inner and outer permanent magnets 8b and 8a have the same thickness shape, the magnetic material having the larger residual magnetic flux density is arranged on the backup side (inner peripheral side), so that Similarly, it is possible to sufficiently back up the permanent magnet 8a on the outer peripheral side.

In the above first and second embodiments, the example in which the four-pole permanent magnet 8 is used has been shown, but other numbers of poles may be used. Further, in the second embodiment, the magnetic materials having different residual magnetic flux densities are composed of the ferrite magnets 12 and the neodymium iron magnets 11. However, they may be combined with other cobalt magnets or alnico magnets, and the same system may be used. The combination of magnets having different residual magnetic flux densities may be used. Further, in the above embodiment, each permanent magnet 8
Although a and 8b are made of permanent magnets all the way to the ends, the ends may be made of voids (air layers) or synthetic resin layers. Furthermore, it is possible to combine the feature points of the first embodiment and the feature points of the second embodiment. That is, the present invention is not limited to the above embodiments, and various modifications can be made based on the spirit of the present invention, and these modifications are not excluded from the scope of the present invention.

[0026]

According to the present invention, the permanent magnet having the higher magnetic flux density is arranged on the backup side, and the permanent magnets arranged on the outer peripheral side of the rotor are sufficiently backed up.
It is possible to provide a highly efficient rotor with a permanent magnet that can effectively utilize magnet torque.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a graph showing H-B characteristics of a permanent magnet.

FIG. 3 is a sectional view showing a prior invention.

FIG. 4 is a sectional view showing the magnetic field analysis.

[Explanation of symbols]

 3 rotor 3a rotor body 8 permanent magnet 8a permanent magnet on outer rotor side 8b permanent magnet on inner rotor side

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masayuki Jinto 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Hiroshi Ito 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 72) Inventor Yoshinari Asano 1006 Kadoma, Kadoma City, Osaka Prefecture, Matsushita Electric Industrial Co., Ltd. (72) Naoyuki Sumiya, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd.

Claims (2)

[Claims] 1. A rotor comprising a rotor body made of a material having a high magnetic permeability, and a plurality of sets of permanent magnets arranged at two layers per pole in the rotor radial direction with a gap therebetween. The thickness of the permanent magnet located on the rotor inner peripheral side of the permanent magnet having a two-layer structure and having a circular arc shape that is convex in the centripetal direction of the rotor is 3% of that of the permanent magnet located on the rotor outer peripheral side.
A rotor with a permanent magnet, characterized in that it is formed with a thickness not less than the above. 2. A rotor comprising a rotor main body made of a high magnetic permeability material, and a plurality of sets of permanent magnets embedded in the rotor main body in a radial direction of the rotor and spaced at two layers per pole. A permanent magnet located on the rotor inner circumference side of a permanent magnet having a two-layer structure and having a circular arc shape convex in the centripetal direction of the rotor has a residual magnetic flux density of 3 relative to the permanent magnet located on the rotor outer circumference side. A rotor with a permanent magnet, which is characterized by being formed of a magnetic material having an increase of at least%.